When bone integrity is threatened by surgical procedure, trauma, infection, congenital malformation, tumor growth, or degenerative diseases bone grafting can be used to encourage the affected bone to regenerate and heal. A bone graft functions like cancellous bone because it supports new tissue growth by providing the bone and blood cells with a matrix through which to interweave as the bone and blood cells reconnect bone fragments. For a bone graft to be successful, three processes that mimic natural events in cancellous bone should take place: osteoinduction, osteogenesis, and osteoconduction. Osteoinduction is the biologically mediated recruitment and differentiation of cell types essential for bone. Osteogenesis is the process of bone formation through cellular osteoblastic activity, which is dependent upon the presence of osteoprogenitor stem cells. Lastly, osteoconduction is the apposition of growing bone to the three-dimensional surface of a suitable scaffold provided by the graft.
Orthopedists are currently using a variety of materials that enhance, to various degrees, these three processes. The basic types of bone substitutes, which are sometimes used alone and sometimes in combination, comprise the autograft, cadaveric allograft, xenograft, and several types of graft materials.
Ideally, materials used for bone grafts will provide for osteogenesis, osteoinduction, and osteoconduction, resulting in vigorous new bone growth that will repair the defect. One effective bone graft material in current use is the autogenous cancellous bone graft. However, survival of intrinsic osteogenic stem cells in the autograft is not optimal, and the harvesting process (generally from the iliac crest) results in considerable pain and morbidity to the patient. As a result, alternative bone-grafting strategies have been investigated. The development of composite grafts that combine synthetic or partially synthetic cancellous bone void fillers with autogenous bone-forming cells could simplify and improve grafting procedures.
There have been devices in the art which allow for the mixing of bodily fluids within a syringe comprising inorganic particles and morsels. Few of these devices, however, provide a device that allows for the formation of a biologically active composite capable of fostering osteoinduction, osteogenesis, and osteoconduction.
For example, U.S. Pat. No. 4,551,135 (“Gorman”), incorporated herein by reference in its entirety, discloses a syringe for the extrusion of a semi-plastic mass. This dispensing syringe has a barrel which may be pre-loaded with a semi-plastic mass or one component of a multi-component plasticizable mixture. Fluid may be injected into the syringe to add a liquid component to the dispensing syringe. Since the liquid component is injected into the dispensing syringe, the Gorman device has a structural limitation that calls for a vent hole. It appears that it is not foreseen that such a device may be used to mix a fluid and a mass using vacuum pressure or suction.
U.S. Pat. No. 4,065,360 (“Kreb”), incorporated herein by reference in its entirety, discloses a syringe device for drawing fluids directly into cavities that can be sealed by the syringe's piston. The syringe includes a hollow housing, a movable piston, at least one culture cavity in the walls of the housing, and a sealing means about the periphery of the movable piston. Fluid is drawn into the cavities when the piston is moved outward from the housing. Once the piston is moved inward, the cavities are sealed and the fluid is allowed to intermix with whatever culture medium is chosen. In this device, however, the cavities are separate from the material chamber and the fluid and medium are only allowed to mix when the piston is closed. This also only allows for a relatively small amount of material to be imbibed by the syringe.
U.S. Pat. No. 4,801,263 (“Clark”), incorporated herein by reference in its entirety, discloses a device for placing osseous implant substances into interdental alveolar bone defects. The device includes a syringe barrel, a syringe plunger member having a piston rod, grasping members attached to an external surface of the syringe barrel, and a threaded nozzle coupler attached to the exterior of the barrel member for allowing an extended nozzle member to be attached to the syringe barrel. This device, however, is incapable of housing a composite and simultaneously imbibing the composite with a fluid.
U.S. Pat. No. 5,772,665 (“Glad”), incorporated herein by reference in its entirety, discloses a device for mixing a pharmaceutical composition and storage for an extended period. The device has a hollow body having an outlet sealed by a removable closure, a plunger within the hollow body, and a chamber for housing the pharmaceutical composition. Fluid can be added to the chamber by withdrawing the plunger upward and allowing water to enter through the lower end or by placing the lid on the lower end, removing the plunger and pouring/injecting water into the upper opening. When the filling is complete, either the lid is applied to the lower end or the plunger is re-inserted into the hollow body, respectively. However, in one embodiment, the lower end of this device is not a syringe tip and one could not use it to aspirate material held within its chamber with fluids drawn directly from the body. In a second embodiment where an injection needle may be fitted onto the Luer cone, the device is incapable of containing a composite that fills the material chamber and then aspirating that composite via vacuum infiltration with bodily fluids without the use of its plunger because the non dispensing end is a handle attached to an actuating rod. It cannot accommodate a secondary needle or vacuum pump.
U.S. Pat. Nos. 5,824,084 and 6,049,026 (referred to herein collectively as “Muschler”) disclose a method of preparing a composite bone graft and apparatus for preparing an implantable graft, respectively, which includes a porous, biocompatible, implantable substrate, a container for retaining the substrate and for permitting flow of a bone marrow aspirate suspension (bone marrow aspirate that may include an isotonic solution and an anti-coagulant) completely through the substrate into an effluent container for receiving effluent of the bone marrow aspirate suspension from the container. Muschler also teaches a graft having an enriched population of connective tissue progenitor cells, the graft being the resultant product of the disclosed method and apparatus.
There is a need to provide for the formation and delivery of a highly porous, inorganic substrate that is rendered biologically active by the aspiration of a biological material into the device. Further, there is a need in the art to provide a method for restoring an osseous void that may be employed in situations that require the use of a bone void filler for filling voids or gaps that are not intrinsic to the stability of the bony structure of the skeletal system. Moreover, there is a need in the art to provide a kit that can form a biologically active composite and deliver the composite mass into an osseous void thereby restoring the void.